The present invention relates generally to bladder nuclear matrix proteins, called “NMPs” here, and more specifically to novel nuclear matrix proteins of the bladder which are associated with cell-proliferative disorders.
The early diagnosis of bladder cancer is central to the effective treatment of the disease. Currently, there are no methods available to easily and specifically identify the presence of bladder cancer cells. The prevailing technique for diagnosis of bladder cancer is to identify bladder cancer cells by morphological examination of the cells by a pathologist. A cellular hallmark of the transformed phenotype is abnormal nuclear shape, the presence of multiple nucleoli and altered patterns of chromatin organization. Nuclear structural alterations are so prevalent in cancer cells that they are commonly used as a pathological marker of transformation for many types of cancer. Nuclear shape is determined in part by the nuclear matrix, the dynamic skeleton of the nucleus.
The nuclear matrix is the structural component of the nucleus that determines nuclear morphology, organizes the DNA in a three-dimensional fashion that is tissue specific, and has a central role in the regulation of a number of nuclear processes including the regulation of gene expression. The nuclear matrix plays a central role in the regulation of important cellular processes such as DNA replication and transcription. Getzenberg, J. Cell Biochem. 55: 22-31 (1994). The nuclear matrix also forms the framework or scaffolding of the nucleus and consists of the peripheral laminas and pore complexes, an internal ribonucleic protein network, and residual nucleoli. Berezney et al., Biochem. Biophys. Res. Comm. 60: 1410 -17 (1974). The nuclear matrix consists of approximately 10% of the nuclear proteins and is virtually devoid of lipids, DNA and histones. Fey et al., Critical Reviews in Eukaryotic Gene Expression 1: 127-44 (1991).
A majority of the known NMPs are common to all cell types and physiologic states. A number of NMPs may be unique to certain cell types or states. The composition of NMPs and their structure are altered by mitogenic stimulation and the induction of cellular differentiation. The nuclear matrix contains a number of associated proteins that have been demonstrated to be involved in transformation. While examining hepatoma nuclear matrix proteins, Berezney et al. first showed that the nuclear matrix is altered in transformation. Berezney et al., Cancer Res. 39: 3031-39 (1979). Fey and Penman demonstrated that tumor promoters induce a specific morphologic signature in the nuclear matrix-intermediate filament scaffold of kidney cells. Fey et al., Proc. Nat'l Acad. Sci. USA 81: 859-66 (1984). Fey and Penman went on to demonstrate that the pattern of NMPs differed between normal and tumorigenic cell lines. Fey et al., loc. cit. 85: 121-25 (1989). More recently, an antibody to a nuclear matrix protein, termed NM-200.4, was raised from the breast carcinoma cell line T-47D. Weidner et al., Am. J. Path. 138: 1293-98 (1991). This antibody reacts strongly with human breast carcinoma specimens as well as specimens from lung, thyroid, and ovarian cancers, but does not react with normal epithelial cells of similar origin, raising the possibility of the use of certain anti-NMP antibodies as diagnostic tools.
Two urine-based tests that are commercially available are NMP22 and BTA. The reported sensitivity of the NMP22 test ranges between 68.5% and 88.5% while its specificity ranges from 65.2 to 91.3%. See, e.g., Dey, P., Clin. Chim. Acta 340:57-65 (2004). The reported sensitivity of the BTA stat test ranges from 57 to 83% and specificity varies from 68 to 72%. Another protein currently being researched for the detection of bladder cancer, survivin, has a high potential specificity at 94%; however, the sensitivity is only 64%. See Shariat et al., J. Urol. 171:626-630 (2004). As such, the use of these urine markers in the detection of bladder cancer is limited by their somewhat poor sensitivity and specificity.
Likewise, the current methods applied in the detection of bladder cancer lack the sensitivity required for the detection of low grade tumors. It is very important to detect bladder cancer in the early stages because the 5-year survival rate is 94% when this cancer is detected early at a localized stage. The current “gold standard” to detect bladder cancer is cystoscopy, which is an invasive test that involves inserting a scope into the urethra. Cytology is commonly used but lacks sensitivity. Cytology has a reported specificity of 94% but the sensitivity is only approximately 55%. See Glas et al., J. Urol. 169:1975 -1982 (2003). Therefore, there is a great need for a test that is both sensitive and specific that is noninvasive and can easily be sampled over time.